JP2003035590A - Coaxial type electronic balance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-priced, high-precision electronic balance which eliminates high-precision processing of machined parts such as a knife edge and by deleting a supporting point, a weight point, a force point, and a Roberval mechanism connecting the three points, and which eliminates experienced skills by simplifying assembly processes. SOLUTION: The coaxial type electronic balance has a sample suspending hook 3, a driving coil 7, a differential coil 8, and a core 9 which are coaxially placed on the force point. The supporting point part is a perfectly fixed torsion balance system provided with a piano wire 10 under a predetermined tension. The electronic balance also has weight-point balance tare correcting weights 5, 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic balance for use in detecting the wetting force of a solder wetting tester.

[0002]

2. Description of the Related Art An electronic balance is used as a force detector for detecting a wetting force in a solder wetting tester, which is used as an instrument for evaluating solderability of electronic parts.
The electronic balance has a fulcrum, an emphasis point, and a force point portion supported by a knife edge, and has a pin mechanism. Further, a differential transformer is arranged at the power point portion, and a horizontal balancing drive coil is arranged at the important point portion, so that the force point portion is displaced by a piston and has a Roberval mechanism.

When a force acts on the force point and displacement occurs in the core of the differential transformer, the horizontal balance of the balance is lost, and the horizontal balance drive coil at the important point feeds back a horizontal balance balancing current proportional to this displacement. It is constantly set to keep the balance horizontal.

In the above-described structure, frictional force is generated at each contact portion due to the processing precision of the knife edge portion supporting the fulcrum, the emphasis point and the force point portion and the assembling precision of the balance, and this cannot be ignored in many cases. The processing and assembly of the electronic balance had to rely on the skill of a skilled technician.

[0005]

DISCLOSURE OF THE INVENTION The present invention eliminates a step requiring precision machining of a machined part in an electronic balance used as a force detector or the like for detecting a wetting force in a solder wetting tester. The task is to simplify the assembly process and eliminate the need for craftsmanship.

In the present invention, by solving the above problems, the production process of electronic balance production is stabilized, the process control is facilitated accordingly, and the material cost in electronic balance production is reduced, which is relatively inexpensive. Moreover, the purpose is to supply a highly accurate electronic balance.

[0007]

In view of such circumstances, as a result of earnest research, the inventors have eliminated precision machining of machined parts in the manufacture of an electronic balance, simplifying the assembly process and eliminating the need for craftsmanship. He found a epoch-making electronic balance manufacturing method and completed the invention.

[0008] The fulcrum, the emphasis point and the knife edge of the force point, and the pin mechanism that supports this are removed to make a direct connection system, and the fulcrum section is a torsion bar that applies a certain tension to the piano wire and is completely fixed to the balance arm. Use the torsion balance method. At this time, as a method of fixing the piano wire and the balance arm portion, for example, there is a method of fixing using a tap handle chuck, but the present invention is not limited to this.

A differential transformer consisting of a differential coil and a core is used at the power point, a horizontal balancing drive coil is arranged on the coaxial extension, and the placement of the differential transformer and the drive coil is focused on the power point. Instead of being dispersed, both are coaxially divided or arranged, or are arranged coaxially as a hybrid structure in which they are integrated.

The weighting part is provided with a weight loading part for tare correction of the balance including the mass of the force point part, and a current proportional to the displacement of the force point part is supplied to the horizontal balance drive coil to keep the balance horizontal and highly accurate. Set so that various load measurements are possible.

The differential transformer used in the coaxial electronic balance of the present invention is compared with the conventional electronic balance by increasing the excitation frequency from 3 KHz conventionally used in the conventional electronic balance to 1.5 MHz. And the transformer volume is about 1/2
Therefore, it is possible to reduce the size and weight.

[0012]

The present invention will now be described in detail with reference to the drawings. FIG. 1 is a schematic view showing the mechanism of a conventional electronic balance.
A fulcrum located in the center of the balance and the left and right sides of the fulcrum are symmetrically arranged, and they are supported by a knife edge and connected by a Roberval mechanism (1). A horizontal balance drive coil (2) is arranged in the emphasis portion, and a sample suspension hook (3) and a differential transformer (4) are arranged in the force application portion.

The sample is loaded on the balance and the differential transformer (4)
When the core part of the is displaced, the horizontal balance of the balance is lost,
As a result, in order to maintain the horizontal balance, the drive coil (2) at the important point is fed back with a horizontal balance balancing current proportional to this displacement, so that the balance is constantly maintained in the horizontal balance.

FIG. 2 is a schematic cross-sectional view of the coaxial electronic balance of the present invention, and FIG. 3 is a schematic cross-sectional view of the fulcrum portion in a direction perpendicular to this. The fulcrum that existed in the conventional electronic balance shown in FIG.
The knife edge and pin mechanism that supports the emphasis point and the point of emphasis are deleted, and it is a direct connection method. In addition, there is no Roberval mechanism (1) in which the force point part displaces the piston, and the piano wire (10) is fixed to the fulcrum part by using the piano wire fixing chuck (11), and the torsion balance system acts as a torsion bar. Has become.

In FIG. 2, the drive coil (7), the differential coil (8), and the core (9) are separately arranged on the extension of the force point portion, but they are integrated to form a hybrid coil structure. It can also be placed on a coaxial extension. In any case, in the conventional balance, the coaxial transformer of the present invention is characterized in that the differential transformer and the drive coil, which are symmetrically arranged in the force point portion and the emphasis portion, are arranged coaxially with the force point portion. .

In use, the balance is adjusted by the balance adjustment (5) and the adjustment weight (6) for tare correction of the balance including the mass of the force point. When loaded on the power point, it becomes unbalanced in proportion to the external force. Therefore, a current proportional to the displacement of the power point is applied to the horizontal balance drive coil (7) to keep the balance horizontal and highly accurate. Set so that the load can be measured.

[0017]

EXAMPLES The results of evaluating the static and dynamic characteristics of the coaxial electronic balance of the present invention will be described in examples.

[0018]

Example 1 A reference weight was sequentially loaded on the sample hanging hook (3) at the power point, and the linearity of the voltage output of the coaxial electronic balance with respect to this was confirmed. The results are shown in Table 1.

[0019]

[Table 1]

[0020]

[Example 2] As a method for evaluating the dynamic characteristics of the coaxial electronic balance of the present invention, the load is rapidly reduced from the rated load (100% load) to the unloaded state for each range (2 to 50 mN). The voltage output of the balance was recorded with a digital recorder. As an example of the measurement result, a graph when the measurement range is 5 mN is shown in FIG. The results obtained were equal to or better than those of the conventional balance.

[0021]

The electronic balance of the present invention has a structure that does not include a knife edge and a Roberval mechanism that require precision machining and is easy to assemble. However, both static and dynamic characteristics are equal to or higher than those of a conventional knife edge balance. It has performance and is useful for detecting the wetting force of a solder wetting tester.

[Brief description of drawings]

FIG. 1 is a schematic view of a cross section of a conventional balance.

FIG. 2 is a schematic view of a cross section of a coaxial balance according to the present invention.

FIG. 3 is a schematic view of a longitudinal section of a coaxial balance according to the present invention.

FIG. 4 is a relationship diagram between time and output voltage obtained when the measurement range is 5 mN.

[Explanation of symbols]

1 Roberval mechanism 2 drive coil 3 Sample suspension hook 4,7 differential transformer 5 Balance adjustment 6 Adjustment weight 8 differential coils 9 cores 10 piano wire 11 Piano wire fixing chuck

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshiyuki Osawa             1-15-17 Hino Honcho Stock Market, Hino City, Tokyo             Inside the company (72) Inventor Takeshita             1-15-17 Hino Honcho Stock Market, Hino City, Tokyo             Inside the company

Claims (4)

[Claims] 1. An electronic balance, in which a fulcrum, a force point and a knife edge of an emphasis point are deleted, a differential transformer, a balance horizontal balance feedback electric magnet are provided on the coaxial extension of the emphasis point, and a balance tare correction is performed at the emphasis point. A torsion balance type coaxial electronic balance with a weight loading section and a fulcrum section that applies constant tension to the piano wire. 2. An electronic balance, which is a coaxial transformer having a differential transformer and a balance horizontal balance feedback electric magnet having an integrated hybrid coil structure. 3. The coaxial electronic balance according to claim 2, wherein the electronic balance has a mechanism in which a Roberval mechanism is omitted. 4. The coaxial electronic balance according to claim 2, wherein the excitation frequency of the differential transformer is increased to reduce the volume and weight of the portion as much as possible. electronic balance.